NEW DELHI >> India’s inadequate government-run tuberculosis treatment programs and a lack of regulation of the sale of drugs that fight it are responsible for the spiraling number of drug-resistant cases that are difficult to treat, health activists said Friday.

India adds an estimated 99,000 cases of drug-resistant TB every year, but only a tiny fraction of those infected receive the proper drugs to treat the stubborn disease through the government-funded program. Friday marks World Tuberculosis Day.

The original form of the disease can be easily cured by taking antibiotics for six to nine months. But if that treatment is interrupted or the dose is cut down, the bacteria battle back by mutating into a tougher strain that can no longer be killed by standard drugs making it harder and more expensive treatment.

The easy availability of TB drugs in the private market and the casual over-the-counter sale of antibiotics is fueling the development of drug resistance, Piero Gandini, head of Doctors Without Borders in India, said in a press statement.

“There is an urgent need for regulatory control of sale and administration of TB drugs in the private sector,” he said.

The organization and other health groups also said that India’s TB control program provides treatment to patients only on alternate days. They argue it increases the risk that patients, most of whom are poor daily wage laborers, will miss doses, another factor responsible for drug-resistant strains of TB.

Patients also increasingly turn to private doctors who often do not understand how to properly treat TB or the risks of increasing drug resistance by prescribing the wrong drugs.

The Indian government had no response Friday to requests for comment on the activists’ allegations.

In January, Indian doctors reported the country’s first cases that appeared to be “totally drug resistant,” a long-feared and virtually untreatable form of the killer lung disease.

The Indian hospital that saw the initial cases tested a dozen medicines and none of them worked. However, the Indian government later questioned the findings, saying the World Health Organization has not defined the term “totally drug resistant” tuberculosis.

If a tuberculosis case is found to be resistant to the two most powerful drugs, the patient is classified as having multi-drug-resistant TB. An even worse classification of TB — one the WHO accepts — is extensively drug-resistant TB, a form of the disease that was first reported in 2006 and is virtually resistant to all drugs.

An estimated 20 percent of the world’s multi-drug-resistant cases are found in India, which is home to a quarter of all types of tuberculosis cases worldwide.